Newb looking for project advice
The thing hollow is kind of uncertain naming. Blender use surface based model for manipulate, which only surfaces are defined in your scene. So yes, every thing you see in your model can be a hollow thing by its model properties.

Maybe you are asking a closed surface behavior after manipulating? In that case, making a shell for the rocket will be a better idea. Using Solidify Modifier can make the object getting a thickness shell surface. So when you look inside the rocket through the tiny window, the surface will not be the wrong direction (backface).

But when the backface is not a consideration. You don't need to solidify it if the view is OK with backface as below: